OS Maps is a mobile app that offers detailed, up-to-date maps of the USA for outdoor enthusiasts. The app provides multiple map layers to suit any activity, including topographic and aerial maps, and allows users to plan unlimited trails and discover new places. Users can search for the best trails in an area as rated by fellow outdoor enthusiasts and plot their own trail to follow, share, and record. The app also offers offline viewing and downloading of maps, as well as live GPS location tracking and off-course alerts to keep users safe on the trail. OS Maps is available on every device, including desktop and Wear OS smartwatches, and offers an auto-renewing monthly or yearly subscription for premium access.

OS Maps is a useful tool for planning outdoor activities, with an automatic "snap-to-path" feature that makes route planning easy. The app also allows users to record, review, and relive their activities, with an activity tracking feature and activity history dashboard. Users can print copies of trails and maps to take with them, and the app offers unlimited printing. However, users should be aware that using GPS constantly can dramatically decrease battery life.

OS Maps is regularly updated to improve stability and add extra features, and user feedback is important to the developers. The app's terms and conditions and privacy policy can be found on the OS Maps website.